If they squat successfully, they become tenants. Then you have to go through the multi-month process to evict them legally.
Re: 13 - had this happen in a county in Western NY several years ago, where some relatives live. Some meth heads broke into a house of some snowbirds who were in Florida for the winter. They were prepping the place to cook meth which essentially ruins the room in which they cook.
Some neighbors down the road saw cars one day in the driveway and called a couple of “friends” to check on the house. The friends checked in and the squatters said they had permission from the owner to live there. The squatters were told they had 1 hour to get out of the house while the friends waited there. Once they got their crap out, the sheriff was called and they busted the people about five miles away with already cooked meth from a previous house they had squatted at.